Author Institution: Kenyon College, Gambier, OhioThis paper reports, for solutions of 0.001 M uranyl sulfate and 0.005 M oxalic acid, a 10-degree temperature coefficient, up to 85°C (using a base temperature of 25°) of 1.02±0.01 at 254 m/x. Measurements in more dilute solutions show a decrease to approximately unity at 0.00025 M uranyl sulfate0.00125 M oxalic acid, with indication that it may become less than unity on further dilution. 
Quantum yields measured (using uranyl oxalate as standard), by students under a National Science Foundation  "pilot" undergraduate participation project, on actinometers at 254 rn.fi, were for (1) malachite green leucocyanide, 0.9; (2) monochloroacetic acid, 0.3; and (3) potassium ferrioxalate, 1.24 moles per einstein

Norton, B. M.

The Ohio Journal of Science

Author Institution: Kenyon College, Gambier, OhioThis paper reports, for solutions of 0.001 M uranyl sulfate and 0.005 M oxalic acid, a 10-degree temperature coefficient, up to 85°C (using a base temperature of 25°) of 1.02±0.01 at 254 m/x. Measurements in more dilute solutions show a decrease to approximately unity at 0.00025 M uranyl sulfate0.00125 M oxalic acid, with indication that it may become less than unity on further dilution. 
Quantum yields measured (using uranyl oxalate as standard), by students under a National Science Foundation  "pilot" undergraduate participation project, on actinometers at 254 rn.fi, were for (1) malachite green leucocyanide, 0.9; (2) monochloroacetic acid, 0.3; and (3) potassium ferrioxalate, 1.24 moles per einstein

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No. 4 ROBBER FLIES IN EASTERN UNITED STATES 421SOME MEASUREMENTS ON THE QUANTUM YIELDTEMPERATURE COEFFICIENT OF THE URANYLOXALATE ACTINOMETER AT 254 MM1' "• 3B. M. NORTONKenyon College, Gambler, OhioABSTRACTThis paper reports, for solutions of 0.001 M uranyl sulfate and 0.005 M oxalic acid, a10-degree temperature coefficient, up to 85°C (using a base temperature of 25°) of 1.02±0.01at 254 m/x. Measurements in more dilute solutions show a decrease to approximatelyunity at 0.00025 M uranyl sulfate—0.00125 M oxalic acid, with indication that it maybecome less than unity on further dilution.Quantum yields measured (using uranyl oxalate as standard), by students under aNational Science Foundation "pilot" undergraduate participation project, on actinometersat 254 rn.fi, were for (1) malachite green leucocyanide, 0.9; (2) monochloroacetic acid, 0.3;and (3) potassium ferrioxalate, 1.24 moles per einstein.EXPERIMENTALSolutions were prepared using C.P. uranyl sulfate, 4.87 grams, and C.P. oxalicacid, 6.3 grams, per liter, with dilutions to concentrations shown in Tables I and II.Sources of 254 m/z radiation were two Hanovia arcs; in one set-up, a three-fold resonance arc, SC2537, was placed in a vertical position; in the other, a spe-cially constructed helical arc was used. For the results shown in Series (2) ofTables I and II, radiation from the arcs was filtered by Corning filters CS7-541Presented at the April 24, 1964 meeting of the Ohio Academy of Science, Western ReserveUniversity, Cleveland, Ohio.2NSF Grant G-485.3Manuscript Received May 20, 1965.THE OHIO JOURNAL OF SCIENCE 66(4): 421, July, 1966.422 B. M. NORTON Vol. 66No. 9863. Exposures were made in pairs of cylindrical quartz tubes of 25-mland 50-ml capacities, with diameters of two and three centimeters, respectively.The tubes were placed flush with windows of various sizes, the windows, in someinstances, being so narrow that a nearly flat surface of the tube was presented tothe incident beam. For the values (B), shown as Series (3) of Table I, a 75-mlcylindrical quartz cell with flat faces was set perpendicular to the incident beam.This provided an optical path of 5 cm, thus ensuring complete absorption of254-m/x radiation by the most dilute solutions used. In many runs, the smallertubes were placed inside the larger, the latter containing water serving as a tem-perature-control bath.TABLE Ioencsa)(2)(3)(4)(5)MoiaritiesTube A0.0010.0010.00050.00050.0010.0010.00050.00050.0005UO2SO4-0.00040.00040.0004.005.005.0025.0025.005.005.0025.0025.0025TubeBSame as ASame as ASame as ASame as A.001 .005.0005 .0025.0005 .0025.00025 .00125.00025 .00125H2C2O4-K2C2O40.0120.0020.002.018.003Volumes mlA252525252525252525B252525255050505050TimeS6C.14001400540540150015001100600600500052001500Tem-peraturesA80°26°80°28°25°25°25°25°25°25°28°25°B26°80°28°80°25°25°25°25°80°85°83°80°A gms0.02NKMnO4 c,A B5.471 5.1144.724 5.3311.137 1.0331.239 1.290A gmsO.O2M(NH4)4 Ce(SO4)44.510 7.1764.462 6.9793.172 5.0071.671 2.4111.679 2.358Number of Runs1117o Decomp.(approx.)40402020•2H2O25-3625-35201040<t>AT*T1.0991.0680.971.051.101.09lllllr+io°*T.018.013.995fins. UUo.018.016In Series (4), Corning filter CS7-54 was used; in (5), full radiation from SC-2537 arc.Exposures (always run in pairs) were made using one of three arrangements:the tubes (a) in fixed positions with respect to the arc, (b) mounted on a rotorso that the two solutions were alternately moved in and out of the radiation beamin the case of the vertical arc, and with continuous exposure when rotated insidethe helical arc, and (c) carried on the circumference of a rotating table with thevertical arc fixed in a hole at its center. Stirring was done by motor-driven glassrods, by the up-and-down motion imparted by the rotating table to prongs of athermocouple (used for temperature control), or by the continual shaking causedby eccentric motion.These variations in set-up produced no detectable differences in results.Exposed solutions were washed with a fixed quantity of sulfuric acid intowhite porcelain casseroles and titrated at about 80°C with 0.01 or 0.02 N potas-sium permanganate, using a micro-burette or, more commonly, a weight burette.In some cases, titrations were made electrometrically, using 0.02 M eerie sulfate.Generally, decompositions in one tube were carried out at room temperatureas a reference to keep a check on the radiation output of the arc. Variationsfound were used in adjusting the experimental values for calculation of the ratioslisted in column 0 A T / 0 T , Table I. In a few instances, as illustrated by Series(1) and (2) of Table I, consecutive runs reversing the high and low temperaturein the two cells constituted the procedure used. The last two lines of Series(3), Table 1, show the kind of calculation involved in the great majority of runs.No. 4 URANYL OXALATE ACTINOMETER 423RESULTS AND DISCUSSIONTen-degree temperature coefficients are reported for the actinometer solution(0.01 M uranyl sulfate-0.05 M oxalic acid) by Leighton and Forbes (1930) tobe 1.03 ±.025 at wavelengths 366 m/x and 313 m^u for the temperature range 15°-35°C, and by Norton (1934) as 1.03±.015 at 313 m/x for temperature range 5°-58°C. Heidt and Boyles (1951) report that the coefficient at 254 m/x does notvary from 0° to 95°C over a ten-fold variation in concentrations (0.017 M uranyloxalate with 0.04 M oxalic acid to 0.0017 M and 0.004 M respectively).Results obtained in this project are shown in Table II. Series (1) consists ofmeasurements in full radiation of the SC-2537 arc, Series (2), using the Corningfilter for 254 m/z.TABLE IISeries(1)(2)MolaritiesUO2SO4-H2C2O40.00020.000250.00040.00050.00060.0010.00130.00250.0050.010.00020.000250.00040.00050.001.001.00125.002.0025.003.005.0067.0125.025.05.001.00125.002.0025.005Number ofruns13853459511442419T+10°*T0.985.9991.0041.0061.0131.0191.0171.0261.0251.0331.000.981.0031.0141.025Averagedeviation.006.009The 10-degree temperature coefficients, using room temperature as a base,run from about 1.0 to 1.03 as a function of concentration. In most runs thehigher temperature was about 80°C. Figure 1 shows the results obtained intwo series of runs. In addition to plotting the coefficients vs. the molarities forthe data in Table II, plots were made (in the case of the 0.005 M oxalic acid) ofthe scatter of values of the coefficient-vs.-percentage decomposition and thecoefficient, obtained in runs in which the higher temperatures were varied from40° to 85°C, vs. temperature. No conclusive trends were discernable within theprecision of the measurements. The last column of Table II shows the averageof the deviations from the average of the calculated 10-degree coefficients.Buchi (1924), and Heidt (1942), and others have discussed equilibria involvingformation of photo-sensitive complexes made up of the uranyl ion with oxalicacid and oxalate ions. The variations shown in Table II may be ascribable toshifts in the concentration of photo-sensitive complexes. Hydrolysis may be afactor at high temperatures, and formation of U (IV) may also be a factor. Avery light greenish precipitate has been observed during runs close to the boilingpoint of the solution, while samples of the same solution boiled for the same timein the dark produced no such effect.There was an opportunity to show the data of Table II to two workers in thisfield, Dr. H. E. Zimmerman (University of Wisconsin) and Dr. J. G. Calvert(Ohio State University), and they suggested investigating the effect of increasingthe oxalate concentration in the most dilute uranyl sulfate concentrations. Three424 B. M. NORTON Vol. 66runs, one with excess oxalic acid and two with potassium oxalate, were made,with results shown as Series (4) and (5) of Table I. The inner-filter effect ofexcess oxalate is evident, since, in 5000 seconds exposure, the same solution, with-out excess of oxalic acid or oxlate, extrapolates to about 75% decomposition.Since these three results with excess oxalate are within the scatter of pointsnormally obtained, they are regarded only as tentative. It is planned to use thetechnique described by Pitts et al. (1955) or Porter and Volman (1962) in order tocarry out more readily measurements involving smaller percentage decompositions.URANYL OXALATE MOLARITY OXALIC ACID 5MOLARITY URANYL SULFATE -y-FIG. 1. Ten-Degree Temperature Coefficient of G (Quantum Yield) as Function of Concen-tration.UNDERGRADUATE RESEARCH PARTICIPATION (NSF-485)Since NSF grant G-485 was the first proposal involving undergraduates,approved by the Foundation as a pilot project before adoption of the presentNSF programs designed for undergraduate participation, information is includedabout the subsequent schooling of the students. A purpose of the program isthe encouragement of promising science majors to go on for graduate degrees;a purpose of this paper is to give a follow-up report on this pilot project.The following Kenyon undergraduates participated in preliminary temperaturecoefficient measurements (where these individuals have completed their work forgraduate degrees, it is indicated): K. Williams (Ph.D., U. of Rochester), J. Looker(Ph.D., U. of Illinois), R. Chenen, and W. Waters. T. Wachs, a present senior,has been helpful in measuring absorption spectra.Other studies by undergraduates, using the uranyl oxalate actinometer, de-scribed in interim G-485 reports to NSF, were made by E. Haseley (Ph.D., O.S.U.)and V. Zeman (M.S., M.I.T.) on quantum yield of malachite green leucocyanidewith values at 254 m^u of 0.9 (Dr. Calvert kindly loaned us his intensity reductionNo. 4 URANYL OXALATE ACTINOMETER 425plates); by C. Criss (Ph.D., Purdue) on quantum yield of mono-chloroacetic acid(result 0.3); by D. Sexsmith (Ph.D., U. of Rochester) and V. Zeman, on liquidethyl iodide (at 313 niju in range 0.2 to 0.3); by E. Schrier (Ph.D., R.P.I.) andJ. Clark (B.D., Episcopal Theological School) on ratio of quantum yields of uranyloxalate actinometer at .05 M oxalate to .005 M oxalate, with values from twoseries of measurements of 1.08 and 1.03; and K. Williams and T. Pierce, on thepotassium ferri-oxalate actinometer. Three series (by K.W.) gave quantumyields at 254 m/i of 1.18, 1.29 and 1.26.The quantum yields of the actinometers listed above are in the same rangeas those reported by Calvert and Rechen (1952) for malachite green leucocyanide;by Smith, Leighton, and Leighton (1938) for chloroacetic acid; and by Parker(1953) for potassium ferrioxalate. It is noted that the former yield of unity forchloroacetic acid is still being used in at least two current physical chemistrytexts. The result of 0.3 (Smith, et al., 1938) was confirmed by C. Djerassi(Kenyon senior thesis, 1942) and by a number of other undergraduates in sub-seauent years as a laboratory exercise in the regular physical chemistry course.REFERENCESBuchi, P. F. 1924. Die Quantenempfindlichkeit der Uranyloxalatphotolyse. ZeitschriftPhysik Chem. I l l : 269.Calvert, J. G. and J. L. Rechen. 1952. Precision Actinometry at Low Light Intensities withMalachite Green Leucocyanide. J. Am. Chem. Soc. 74: 2101.Heidt, L. J. 1942. The Photo-sensitive Complexes in the Phototypes of Uranyl Oxalate. J.Phys. Chem. 46: 624.Heidt, L. J. and H. B. Boyles. 1951. Influence of Several Variables Encountered in Photo-chemical Work upon the Intensity of X254m t^ Produced by a Quartz Mercury Vapor Lampof the Low Pressure Type Operating in Water at 0° to 95°. J. Am. Chem. wSoc. 73: 5729.Leighton, W. G. and G. S. Forbes. 1930. Precision Actinometry with Uranyl Oxalate. J.Am. Chem. Soc. 52: 3139.Norton, B. M. 1934. Quantum Yields in Photodecomposition of Liquid Ethyl Iodide at 3130,2654 and 2537A. J. Am. Chem. Soc. 56: 2294.Parker, C. A. 1953. A New Sensitive Chemical Actinometer. I. Some Trials with Potas-sium Ferrioxalate. Proceedings Royal Society A220: 104.Pitts, J. N., J. D. Margerum, R. P. Taylor, and W. J. Brim. 1955. Determination of LightIntensities with a High Sensitive Uranyl Oxalate Actinometer. J. Am. Chem. Soc. 77:5499.Parter, J. and D. H. Volman. 1962. Uranyl Oxalate Actinometer for Microphotochemistry.J. Am. Chem. Soc. 84: 2011.Smith, R. N., P. A. Leighton, and W. G. Leighton. 1938. The Quantum Yield of Mono-chloroacetic Acid Hydrolysis. J. Am. Chem. Soc. 61: 2299.

Some Measurement on the Quantum Yield Temperature Coefficient of the Uranyl Oxalate Actinometer at 254 Mu1,2,3

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Some Measurement on the Quantum Yield Temperature Coefficient of the Uranyl Oxalate Actinometer at 254 Mu1,2,3

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